Boeing 737

The Boeing 737 is a short- to medium-range twinjet narrow-body airliner. Originally developed as a shorter, lower-cost twin-engined airliner derived from Boeing's 707 and 727, the 737 has developed into a family of ten passenger models with a capacity of 85 to 215 passengers. The 737 is Boeing's only narrow-body airliner in production, with the 737 Next Generation (-700, -800, and -900ER) variants currently being built. Production has also begun on the re-engined and redesigned 737 MAX, which is set to enter service in 2017.

Originally envisioned in 1964, the initial 737-100 made its first flight in April 1967 and entered airline service in February 1968 at Lufthansa. Next, the lengthened 737-200 entered service in April 1968. In the 1980s Boeing launched the -300, -400, and -500 models, subsequently referred to as the Boeing 737 Classic series. The 737 Classics added capacity and incorporated CFM56 turbofan engines along with wing improvements.

In the 1990s Boeing introduced the 737 Next Generation with multiple changes including a redesigned, increased span laminar flow wing, upgraded "glass" cockpit, and new interior. The 737 Next Generation comprises the four -600, -700, -800, and -900 models, ranging from 102 ft (31.09 m) to 138 ft (42.06 m) in length. Boeing Business Jet versions of the 737 Next Generation are also produced.

Boeing 737 Classic

The Boeing 737 Classic is the -300/-400/-500 series of the Boeing 737, so named following the introduction of the -600/-700/-800/-900 series. They are short- to medium- range, narrow-body jet airliners produced by Boeing Commercial Airplanes. The Classic series was introduced as the 'new generation' of the 737. Produced from 1984 to 2000, 1,988 aircraft were delivered.

Development and design

Following the success of the Boeing 737-200 Advanced, Boeing wanted to increase capacity and range, incorporating improvements to upgrade the plane to modern specifications, while also retaining commonality with previous 737 variants. Development began in 1979, and in 1980 preliminary aircraft specifications were released at the Farnborough Airshow. In March 1981, USAir and Southwest Airlines each ordered 10 aircraft, with an option for 20 more.

The new series featured CFM56 turbofan engines, yielding significant gains in fuel economy and a reduction in noise, but also posing an engineering challenge given the low ground clearance of the 737. Boeing and engine supplier CFMI solved the problem by placing the engine ahead of (rather than below) the wing, and by moving engine accessories to the sides (rather than the bottom) of the engine pod, giving the 737 a distinctive non-circular air intake.

Boeing 737 MAX

The Boeing 737 MAX is a new series of aircraft being developed by Boeing Commercial Airplanes. It is the successor of the Boeing 737 Next Generation. The 737 MAX is the fourth generation of the 737 family. The primary change is the use of the larger and more efficient CFM International LEAP-1B engines and modifications to the airframe. As of December 2015, Boeing has 3,072 firm orders for the aircraft. The 737 MAX first flew on January 29, 2016, nearly 49 years after the maiden flight of the 737 on April 9, 1967; the MAX is scheduled for first delivery in 2017.

Development

Since 2006, Boeing has discussed replacing the 737 with a "clean-sheet" design (internally named "Boeing Y1") that could follow the Boeing 787 Dreamliner. A decision on this replacement was postponed, and delayed into 2011. In November 2014, it was reported that Boeing intends to replace the 737 by 2030 with a new airplane, possibly with a composite airframe, dubbed as the Boeing Y1.

In 2010, Boeing's competitor, Airbus, launched the Airbus A320neo, which boasted new engines which improve fuel burn and operating efficiency. The decision was met with positive reaction by many airlines and they began making major orders for the aircraft. Pressure from airlines for more fuel efficient aircraft forced Boeing to shelve plans for developing a replacement aircraft, the Boeing Y1, and instead focus on upgrading the 737. On August 30, 2011, the company's board of directors approved the 737 MAX project. Boeing predicted that the 737 MAX will provide a 16% lower fuel burn than the current Airbus A320, and 4% lower than the Airbus A320neo. Boeing expects the 737 MAX to meet or exceed the range of the Airbus A320neo. The first 737 MAX aircraft is scheduled to be delivered in 2017.